It's incorrect because the package is linked to two separate executables, there's no chance there will be duplicate symbols. This is the project structure, and I do not want to use dynamic libraries.
Target A: A command line program
Target B: A XPC service
Target C: A SwiftUI application using the XPC service
Targets A and B use the same package, a set of "helper" Swift files.
Target A is used by Target B, and Target B is used by Target C. They are all separate processes, all linked independently. There is no reason whatsoever for Xcode to detect these as duplicate linking and fail the build.